You cannot increase the sensitivity of film by 'pushing'. It's a waste of time to try. Underexposure cannot be remedied by overdevelopment. The sensitivity of film is determined at manufacture. Faster films have more latitude, and that can be confusing. They can be under-exposed a little more than slow films can. Fast films have a greater range of crystal sizes. Slow films have only very small crystals, medium-speed films have a wider range of crystal sizes, and fast films have the widest.

Maybe we should look at what the OP needs, not at what the rules are......
If what he needs is a usable neg that would otherwise be trashed, the "push" is his answer. The shadow detail he will lose may not be important if the subject of the picture is reasonably well exposed.
Personally, shadow detail to me is over-rated. Would rather rather have hi-lite detail. My eye goes to the brighter part of a picture first since that is probably the most important part.

Having said all that, I would reconsider using D-76 , but if that is what you have, go for it.
Jim

Maybe we should look at what the OP needs, not at what the rules are......
If what he needs is a usable neg that would otherwise be trashed, the "push" is his answer. The shadow detail he will lose may not be important if the subject of the picture is reasonably well exposed.
Personally, shadow detail to me is over-rated. Would rather rather have hi-lite detail. My eye goes to the brighter part of a picture first since that is probably the most important part.

Having said all that, I would reconsider using D-76 , but if that is what you have, go for it.
Jim

It doesn't work, that was my point. The sensitivity of film is determined in manufacturing.

If push-processing were to lead to total mish-mash, why would the manufacturer lead a photographer on to totally ruin his film?
Is this a diabolical plot by the manufacturer to put itself out of business, or do they see possibilities that you don't?
I understand what you are trying to say; you have said it for years. So many people don't agree with you.
Jim

If push-processing were to lead to total mish-mash, why would the manufacturer lead a photographer on to totally ruin his film?
Is this a diabolical plot by the manufacturer to put itself out of business, or do they see possibilities that you don't?
I understand what you are trying to say; you have said it for years. So many people don't agree with you.
Jim

What are you talking about? The latitude and speed of the film are determined at manufacture. Increasing development does not increase density in the shadow areas, only in the denser areas. Underexposure cannot be remedied by increasing development. I should know, I used to do it all the time until I realized my photos looked like ca-ca.

Fast films develop slower and have more latitude than slow films because they have a bigger range of crystal sizes.

To repeat:
Why do the makers give push-processing times? I have no quarrel with your statements. As I said, maybe the OP is looking for a usable neg rather than one that has "shadow detail" and a full range of "beautiful, full tones." Maybe he is looking for a compromise.

pirateoversixty wrote:To repeat:
Why do the makers give push-processing times? I have no quarrel with your statements. As I said, maybe the OP is looking for a usable neg rather than one that has "shadow detail" and a full range of "beautiful, full tones." Maybe he is looking for a compromise.

I don't know why they do that. They never used to do it, and Kodak has stated that a one-stop underexposure needs no additional development. They don't explain with sufficient emphasis that extending development rapidly increases fog, grain and contrast, and does not actually compensate for the underexposure. Nothing can (well, there is chemical latensification, but it is a rarely-used technique).

A lot of manufacturers do list times for push processing, but Ornello is correct in stating that every film has an optimal speed at which it should be exposed to get the fullest tonal range and most accurate contrast. Some films have more latitude than others, allowing them to be exposed within a wider range of speeds. Push processing typically increases apparent grain and contrast at the expense of tonality. Nevertheless, there are reasons you might want to push process film. When there is insufficient light to expose the film at the given ISO, increasing the film speed allows you to make an exposure which you would otherwise be unable to capture. If this is the case, then some loss of quality is less important than not being able to take the image in the first place. Equally, there can be artistic reasons for wanting to increase contrast and/or grain which render the correctness of the exposure as secondary. Shooting and developing film "correctly" is only important if you desire "correct" results. In either case, by modifying the development time you can partially reduce the effect of underexposure.

Digitaltruth wrote:A lot of manufacturers do list times for push processing, but Ornello is correct in stating that every film has an optimal speed at which it should be exposed to get the fullest tonal range and most accurate contrast. Some films have more latitude than others, allowing them to be exposed within a wider range of speeds. Push processing typically increases apparent grain and contrast at the expense of tonality. Nevertheless, there are reasons you might want to push process film. When there is insufficient light to expose the film at the given ISO, increasing the film speed allows you to make an exposure which you would otherwise be unable to capture. If this is the case, then some loss of quality is less important than not being able to take the image in the first place. Equally, there can be artistic reasons for wanting to increase contrast and/or grain which render the correctness of the exposure as secondary. Shooting and developing film "correctly" is only important if you desire "correct" results. In either case, by modifying the development time you can partially reduce the effect of underexposure.

35mm film is capable of delivering fantastic quality if one is willing to make the effort to use optimum exposure and development. Kodak used to make a very fast film (T-Max 3200), but even it was only ISO 800 in reality. There still is Ilford Delta 3200 whose true speed is roughly 1000-1200.

Digitaltruth speaks the truth. A "correct" result exists only in the mind of the person that is satisfied with the results of his efforts. Some prefer a contrastier result than another would consider "correct". Trying to push everybody to aspire to one standard would certainly make for a boring, and certainly less artistic, and innovative, process.

Ornello, some time ago you were going to write a book on photographic processing, and were going to share the fruits of your endeavor with anyone interested. Any news there?
Jim

pirateoversixty wrote:Digitaltruth speaks the truth. A "correct" result exists only in the mind of the person that is satisfied with the results of his efforts. Some prefer a contrastier result than another would consider "correct". Trying to push everybody to aspire to one standard would certainly make for a boring, and certainly less artistic, and innovative, process.

Ornello, some time ago you were going to write a book on photographic processing, and were going to share the fruits of your endeavor with anyone interested. Any news there?
Jim

I wrote it, this was about 6 or 7 years ago. Unfortunately I lost interest in pursuing it because publishers were reluctant to invest in a book about B&W film at this stage, what with digital and all. People should learn how good their results can be from optimizing their technique, then they would be far less interested in off-beat approaches. The greatest power photography has is that it can capture reality. All the most famous and moving photos you can name are significant because of their content, not some manipulation.

pirateoversixty wrote:I guess I have to sign off on this thread. Nothing more to say.
Interesting link on Edgerton.
Jim

The faster the film, the greater the size of the AgBr crystals, and the greater the range of sizes. Slow films have only very tiny crystals, which develop quickly (because they are small) and all about the same time (because they are all about the same size). This is why slow films have less latitude. With all films, in the shadow areas, the most sensitive (largest) crystals are exposed in greater proportions. Thus, shadow areas have the most graininess, but since the shadows are normally very dark in the print, this graininess is not apparent to the eye. When you underexpose, only the very fastest (largest) crystals are exposed, so the apparent graininess increases, because what should be shadow area is being used for mid-tone area. Over-development will not cause the slow grains to develop, because their threshold for exposure has not been reached. There is simply nothing to develop. So, the large grains keep developing (getting larger), and the small ones don't develop at all.